PORTLAND, Ore. (AP) — Oregon officials are seeking more than $27 million in damages over dam repairs they say killed more than half a million Pacific lamprey fish in what they’ve described as one of the largest damages claims for illegal killing of wildlife in state history.

In a claim filed in Douglas County Circuit Court on Friday, the Oregon Department of Fish and Wildlife said that recent repairs to Winchester Dam in the southern part of the state resulted in the death of at least 550,000 juvenile Pacific lamprey, an eel-like fish key to local ecosystems and of cultural significance to many Native American tribes in the region. The fish is also listed as a protected species in Oregon.

“The North Umpqua River’s diverse fish populations are unique within Oregon and are of considerable social, cultural, and economic importance locally and regionally,” the fish and wildlife department said in a news release. “The damages claim seeks reparation for the loss of a valuable public resource.”

The complaint was filed against the Winchester Water Control District along with TerraFirma and DOWL, companies that were contracted, respectively, for dam repairs and fish salvage operations.

The department has accused the defendants, among other things, of unlawful killing of fish and negligence.

Neither DOWL nor Ryan Beckley, president of the water control district and owner of TerraFirma, immediately responded to emailed requests for comment.

Built in 1890 on the North Umpqua River, Winchester Dam is a former hydropower plant that is now privately owned by the water district’s residents, who largely use it for water sports and recreation, according to the complaint.

Environmental groups have long criticized the dam, describing it as an old, disintegrating structure that kills or prevents fish including lamprey and salmon from swimming upstream.

Jim McCarthy, Southern Oregon Program Director of WaterWatch of Oregon, said he hoped the damages claim would mark a turning point for lamprey conservation.

“This is wonderful news for Pacific lamprey which, for too long, have been disregarded and treated as disposable, leading to dramatic declines,” he said. “This is a win for Native American tribes which have worked so hard to raise awareness about the importance and value of these fish, and to restore them.”

The complaint stems from repairs that the Winchester Water Control District requested last year.

To carry out the repairs, the district received authorization from the fish and wildlife department to temporarily drain part of the reservoir behind the dam and close the fish ladder. This, on the condition that it take steps to salvage and relocate fish and make a “sufficient effort” to ensure that no more than 30,000 juvenile lampreys were killed in the process.

When the water drawdown started on August 7, however, those salvaging efforts were not completed, stranding and exposing thousands of lamprey in the sediment, according to the complaint. Two days later, the fish and wildlife department determined that an emergency salvage operation was necessary and recruited employees from across the western side of the state to assist. At least 550,000 lamprey died as a result, the complaint said.

The incident was raised during recent legislative hearings at the state Capitol in Salem. State Sen. Jeff Golden, the chair of the chamber’s natural resources committee, has requested that the departments of Fish and Wildlife, Water Resources and Environmental Quality submit a report to lawmakers in the coming months.

___ Claire Rush is a corps member for the Associated Press/Report for America Statehouse News Initiative. Report for America is a nonprofit national service program that places journalists in local newsrooms to report on undercovered issues.